Process of vulcanizing caoutchouc and product obtained thereby



LORIN B. SEBRELL, OF'AKRON, OHIO, ASSIGNOR 'lO THE GOODYEAR TIRE GOMPANY, OF AKRON, OHIO, A CORPORATION OF OHIO.

PATENT OFFICE.

& RUBBE] rno'cnssor lvirnce ir me cnonrcnouc AND rnonucr onmxnnn TEEREIBY.

"' "1R0 Drawing.

To all whom it May "concern; Be it known that-'IfIionm'; B. SEBRELL, a citizen of the United States, and resident of Al ron',- )hio,* have invented new" and 5 useful Imp'rovmentsih Processes of VuL =caniz ing Cacutchouc and Products Obtained Thereby, of'which the following is a specification; 1 a v y My'invention relates to vulcanized caoutcho'uc products and tof the artfof producing them; with particularreference to the acceleration'of the vulcanization thereof. I

In the manufacture of most rubber articles a compound of rubber, or amixture of caoutchouo and filler, is employed, which is vulcanized by, incorporating in the mix a vulcanizing agent, such as sulfur. Although a mixture of this type will vulcanizewhen subjected to heat for a sufiicient'length of time, it is desirable to employ a catalyst or an accelerating agent which increases'the rate of vulcanization,

thereby reducing the expense of manufacture and improving'the quality of the rubher roducts. There are, of course, a relative y large number of accelerating agents now known to manufacturers of rubber, but

most all of them have particular applications or characteristics which make them so especially'suitable for usein certain types of rubber articles, 'but,'on' the other hand,

they may be objectionable for incorporation in certain other types of articles. Consequently, it is necessary, in the manufacture es of a variety of rubber products, to have various types of accelerators that me be applied as their particular characteristics especially adapt them for use.

It is desirable in'some instances to employ an accelerating egent which" shall be Applieation'nfled August 14, 1923. Serial No. 657,429.

especially powerful, consequently, insure very rapid vulcanlzation to obtain a high quality product for certain purposes.

I have discovered that substituted thioureas obtained from primary aromatic amines containing hydrocarbon residues, otherwise known as hydrocarbon or alkyl groups, more particularly those substituted thio-ureas produced 'by the reaction of carbon bisulfide with aromatic amines having" alkyl substituents in meta position with respect to each other, which class of substituted thio-ureas may be otherwise defined as aryl substituted thio-ureas having alkyl groups in meta position with respect to each other, have the desired property, when used as an accelerator, of effecting a cure in a. Very short time.

The class of chemical com ounds to which the acceleratoncontemplate b fay invention belongs may he represents by the following formula: I

wherein B may be any hydrocarbon or al 1 radical, such as CH A hydrocarbon ra i cal my be either in one phenyl group, as in-; dicat in the formula as above shown, o1i in both phenyl groups as, for example, dimeta-xylyl-thio-urea. The compound represented by this group is prepared by a reaction of carbon bisulfide witli,--4-amin ometa-xylene, which reaction may be represented as follows:

5 one-third of the An accelerator may also be prepared by the reaction of carbon bisulfide with technical gylidine, which is a mixture of the CH: CH:

several xylidines among which may be mentioned the following compounds: 5

CHI

Von. f

CHi I K2,?! k/ 0H.

When technical xylidine is employed to produce an'accelerator by reaction with carbon bisulfide, the product may be an aryl substituted thio-urea having alkyl groups in positions other than. meta, as, for example, in ortho position with respect to each other, the product being, therefore, a mixture of several different thio-ureas.

The process of utilizing my invention may he illustrated b the following example:

100 parts of rubber,

5 parts of zinc oxide, 6 parts of sulfur, and

2.8 parts ofaccelerator.

If such ingredients are thoroughly mixed and subjected to heat at a temperature corresponding to 40 lbs. of steam pressure for twenty minutes, the compound is slightly over-cured, and about fifteen minutes suffices 5 to produce a wellcured product. In order to illustrate the relative curing power of my accelerator, the same compound was utilized with the exception of the amount of accelerator incorporated therein, and in one instance thio-carbanilide was substituted, 2.28 parts being mixed with the ingredients. The weight relations of the amounts of the accelerators being such that equimolar portions were employed. A good cure of the latter compound was'obtained in one hour and, twenty minutes at a temperature corresponding to 40 lbs. of steam pressure.

-A further comparison was made by mixing 2.56 parts of di-ortho-tolyl-thio-ureain 40 the foregoing compound, which was subjected to 40 lbs. of steam pressure for about fifty minutes to obtain a good cure. It will be noted, therefore, that the ineta-irylyhthiourea produces a good cure in substantially time necessary when 'eithen thiocarbanilide or di-ortlio-tolyl-thi'o-urea are utilized in a similar compound. It shows, therefore, that inasmuch as metaxylyl-thio-urea possesses greater accelerat- 5 mg power, it is only! necessary to use approximately one-third as much of the accelcrator upon an equimolar basis to obtain a good cure infl thggame length of time as the other accelerators herein mentioned.

replaced by other ingredients having the same general functions respectively.

Although I have given specific examples a of procedure and have mentioned di metaxylyl-thio-urea as one of the preferred accelerators of the class used in a rubber compound including zinc oxide and sulfur, it will be understood that I do not regard the invention as dependent upon the specific procedure or materials mentioned, except in so far as such limitations are included within the terms of the claims appended hereto. What I claim is: 1. A process of vulcanizing caoutchouc that comprises incorporating with a caout chouc mix an aryl substituted thio-urea having two substituted alkyl groups on one or 7 both benzene rings and vulcanizing the mix.

2. A process of vulcanizing caoutchouc that comprises incorporating with a caoutchouc mix an aryl substituted thio-urea having two alkyl groups in meta position to so each other and vulcanizing the mix. I

3. A process of vulcanizing caoutchouc that comprises incorporating with a caoutchouc mix an aryl substituted thio-urea having two substituted alkyl groups, one of which is in meta position to the other andvulcanizing the mix.

'4. A process of vulcanizing caoutchouc that comprises incorporating with 'a caoutchouc mix a metaozylyl-thio-urea and vul- I canizlng the m x.

5. A process of vulcanizing caoutchouc that comprises incorporating with a caoutchouc mix di-meta-xylyl-th'io-urea and vul canizing the mix.

6. The process of vulcanizing caoutchouc that comprises bringing together under reacting conditions carbon bisulfide and an aromatic amin having two alkyl substituents in meta position with respect toeach other, 100 incorporating the resulting product in the caoutchouc mix and vulcanizing the mix.

7. The process of vulcanizing caoutchouc ,ncting wnditicns together under reearbon bisulficie and Kylieiine, topmdnce an aryl substituted thiourea having twe alkyl groups on each benzene i ring, inoerpomting in e ceentcheuo 8. The process the? cempi'isee bringing 16 acting conditions carbon emme-mem xylene,

the resulting product, mix and vulcaniz ng the of vulcanizing 'cnoutchouc tegether under rebisulfide and 4cincorporating the resnlcing product in e caeuiachcuc mix and vnlcenizin the mix.

5). A vueanizeci cnontehouc product prom dnced by the cnnizing agent reaction of caoubchouc, 21 V111- and an aryl substituted thiemrea. accelerator havingtwo alkyl groups in meta posltion with respect to each other.

19. A vulcanize d caeutchelic product produced by the reaction of caoutcneuc, e veicanizing agent and meta-xylyl-thie-uree as. an accelerator.

11. A vulcanized caeut/chcuc product prr dnced by the reaction of caeutcheuc, a vulcanizing agent and di-meta-xylyLthie-urea as an accelerator. f

12. A vulcanized caoutcheue product prednced by the reaction of caontcheue, a vulcanizing agent and an accelerator formed by the reaction of carbon bisulfide and amino-meta-xylene.

In Witness whereof, I have hereunto signed my name in the presenceof two subscribing Witnesses.

LORIN B. SEBRELL.

Witnesses:

O. E. Em, F. A. Linn.v 

